Ordinary drawers have a outer pull-out rail, intermediate rail and a fixed rail. The outer pull-out rail can glide in the intermediate rail, and the intermediate rail can glide in the fixed rail. Because drawer's rails support mostly vertical and downward pressure from drawer, designers focus on devising upward supporting structure. Designers set several horizontal rollers to support rails to move smoothly when the drawer is heavy. These rollers are set between the outer pull-out rail's horizontal plane and the intermediate rail's horizontal plane. And they also be set between the intermediate rail's horizontal plane and the fixed rail's horizontal plane. However, the three rails, particularly the outer pull-out rail and the intermediate rail will become cantilever structure when drawer is being pulled. At this time, the front part of outer pull-out rail will sag, and the end of the outer pull-out rail will hold up. Although some baffles and idler wheels can be set to lock the neighbouring intermediate rail to decrease above phenomenon, these measures still cannot solve issue completely and cannot satisfy customers' excelsior requirement. Besides, people also find that we cannot control exactly for the gaps' breadth wise shaking which is between the outer pull-out rail and intermediate rail or between the intermediate rail and fixed rail. People will feel the drawer having an additional trend to run to right and left when they drag the drawer. It is not what a high-end product customer expects.
All appearance, the disadvantages of today's products need to be improved.